How bad could it get? America’s ugly election

Buried corpses may change the colours of surrounding plants

Forensic botany

Murder will out

Doing it the old way

Correction

In “The aliens among us”, the cover

leader of the August 22nd edition, we said that 10

31

is ten followed by 31 zeros. It is, of course, one

followed by 31 zeros. Sorry for the mistake.

---

70

Science & technology

The Economist

September 5th 2020

T

hat dreams

contain hidden meanings

is an old idea. The Biblical Book of Gen-

esis, written down about 2,500 years ago,

describes how Joseph, son of Jacob, inter-

preted the Egyptian pharaoh’s dreams of fat

and thin cattle as predicting years first of

plenty and then of famine. In China, mean-

while, the most popular work on dream in-

terpretation has long been the “Zhougong

Jie Meng”, a dictionary of explanations for

weird and wonderful dreams written 500

years earlier still. It is, however, only since

the publication of Sigmund Freud’s treatise

“The Interpretation of Dreams”, in 1899,

that dreams have become a subject of seri-

ous scientific scrutiny. 

Things have moved on since Freud’s

day. His emphasis on violent urges and sex-

ual repression as the roots of dreaming

now looks old-fashioned. Instead, the pre-

mise is that dreams reflect a dreamer’s quo-

tidian experience—either because they are

an epiphenomenon of the consolidation of

memories or because they are a mental

testing ground for ideas the dreamer may

have to put into practice when awake. This

resemblance between dreams and reality is

dubbed the continuity hypothesis by psy-

chologists. Data supporting it, however,

are sparse. Such as exist come from clinical

studies rather than examinations of people

with healthy minds. And the numbers of

participants involved tend to be small.

That is not true, though, of the latest in-

vestigation into the matter. As they de-

scribe in 

Royal Society Open Science

, Ales-

sandro Fogli of Roma Tre University, in

Italy, and Luca Maria Aiello and Daniele

Quercia of Nokia Bell Labs, in Cambridge,

Britain, have analysed thousands of re-

ports of dreams experienced by mentally

healthy people. Using these, they have test-

ed several predictions based on the con-

tinuity hypothesis and found support for

all of them.